The career development and research plans outlined in this Mentored Research Scientist Development Award (K0l) proposal are designed to enable the candidate to independently design and conduct studies that examine the combined importance of genetic and environmental risk factors for the development of depression in children and adolescents. Depression is a chronic condition that often begins early in life and appears to be the result of both genetic and environmental risk factors. Recent studies have suggested that the phenotypic expression of genetic risk for depression emerges during adolescence and appears to be moderated by the presence of behavior-dependent stressful life events. Understanding the pathway(s) by which various stressful environments interact with genetic risk factors to contribute to the onset of depression is crucial for understanding how to successfully treat and/or prevent this debilitating disease. The proposed study will prospectively examine whether the frequency of environmental stressors, particularly behavior-dependent stressors, increases during adolescence and continue to increase thereafter. An important aim of the research plan is to determine whether exposure to specific environmental stressors modifies the familial risk for depression in adolescents at high- and low-familial risk for depression. The candidate is formally trained in psychiatric epidemiology and has research experience in the study of familial and environmental risk factors for depression in children and adolescents. Neal D. Ryan, M.D. and Bernie Devlin, Ph.D. will serve as co-mentors. Coursework and didactic readings in genetic epidemiologic methods, quantitative genetics, molecular genetic techniques, and clinical interviewing techniques are designed to complement the candidates research training and prepare him to become an independent investigator.